泌尿器科領域に於ける日本人胎児の研究 (第2篇)

腎盂, 大・小腎杯の発生並びに発育 (形態) に就いて

抄録

In the urological practice, it has been customary to make roentgenological observations on the position of the kidney and the morphology of the renal pelvis, major and minor calices in detail for determining the diagnosis, indications for operation, therapeutic policy and prognostication. At present, it is even possible to decide on the operation and to predict the prognosis by observing the morphological changes of one minor calyx. However, the position and morphology of these structures are extremely variable such as never encountered in other organs. At all events, the morpholofical classigication and pathological changes of the renal pelvis, major and minor calyces have in most cases been based on adult organs and embryological studies utilizing fetal materials have seldom been undertaken. Despite the fact that investigations on the growth and development of the kidney have now been almost completed, the problems as to the details of post natal development of the renal pelvis or of the ramification of the minor calyx are still little understood. In this laboratory, Takashima (Pyelography in the Japanese fetus, 1958.) made pyelographic observations from different angles on the position and morphology of Japanese fetusef. These studies, however, are based only upon the pyelographic pictures and not upon anatomical findings.
For this reason, the author endeavored to reevaluate the conclusions reached by Takashima on the basis of comparative studies between the histological findings on fixed sections observed under lw-power magnification and the pyelographic pictures. By so doing the growth and development of the pelvis, major and minor calices in the fetal period as to their position and morphology have been investigated. The author's aim is not so much to simply determine their details as characteristics peculiar to the fetus, as to grasp the facts underlying the changes in these organs as well as the pathogenesis of malformations.
The materials employed for the present investigation consisted 50 fetuese selected from 200 out of a total of 400, considered to meet all the requirements for proper and satisfacory observations. After making the pyelograms of these fetuses, the tissue blocks were fixed and cut into microscopic sections, and the findings obtained from these two methods of study have been compared as to their possible interrelationship. The procedure of comparative study involved the varions measurements described below, the resulting ratio having been evaluated on linear and circular graphs. The development and growth of the fetal kidney, the pelvis, major and minor calices in the fetuses calculated to have attained the second month of gestation (eight fetal weeks) to the tenth month (forty fetal weeks) were determined.
1) Development of the kidney. During the period from the second to the tenth month of gestation, the kidney increases approximately thirty times in both transverse and longitudinal diameters, while the volume grows about 27, 000 times. In contrast to such rapid growth and development of the renal parenchyma, the pelvis shows a relatively slow change in development. The ratio of renal growth to pelvic development gradually increases up to the fifth gestation month, but during the period from the fifth to the eighth fetal months this tendency becomes less evident. However, after the nineth month the space occupied by the pelvis again increases, so that it attains the pelvic form resembling that of adult sby protruding outside the kidney. Generally, the pelvis makes its appearance for the first time during the third fetal month, and its size increases 15 times in length and 20 times in width during the tenth month.
2) The ramifications of the major calyx have been classified into 4 types as A, B, C and D, During the second month there are practically no ramifications of the major calyx, but during the third month the portion near the upper pole of the kidney, followed by that in the neigh